Toxins Unit – Investigation IV Lesson 1: Heartburn

Unit IV Investigation IV-X ChemCatalyst Countless products are advertised on TV with the promise of reducing acid indigestion. – What is acid indigestion? What is acidity? – What does acid have to do with your stomach? – How do you think acid “reducers” work?

Unit IV Investigation IV-X The Big Question – What are some characteristics of solutions that are acidic, basic, or neutral?

Unit IV Investigation IV-X You will be able to: Describe the differences among acidic, basic, and neutral solutions.

Unit IV Investigation IV-X – Indicators: A set of substances that respond to other substances with vivid color changes. Notes

Unit IV Investigation IV-X Activity Purpose: This activity will introduce you to a special category of solution. (cont.)

Unit IV Investigation IV-X Safety note: Do not get acids and bases on your skin. In case of a spill, rinse with large amounts of water. Wear goggles. (cont.)

Unit IV Investigation IV-X Substance FormulaCabbage Juice Indicator color Indicator number table salt (aq)NaCl vinegar (aq)C2H4O2C2H4O2 rubbing alcoholC3H8OC3H8O ammonium hydroxide (aq) NH 4 OH distilled waterH2OH2O stomach acid (aq)HCl washing soda (aq) Na 2 CO 3 lemon juiceC6H8O7C6H8O7 drain cleaner (aq)NaOH

Unit IV Investigation IV-X 1470 (cont.)

Unit IV Investigation IV-X Observations when added to CaCO 3 water stomach acid vinegar drain cleaner (cont.)

Unit IV Investigation IV-X Making Sense – Look for patterns in the names, chemical formulas, uses, and properties of the substances you tested. – List four characteristics of acids. – List four characteristics of bases.

Unit IV Investigation IV-X Indicators can be used to identify substances that are acidic, basic, and neutral when dissolved in water. – Acids turn cabbage juice pink and are between 0 and 7 on the universal indicator scale. – Bases turn cabbage juice green or blue and are between 7 and 14 on the universal indicator scale. – Neutral substances do not change color with cabbage juice and are at or very near 7 on the universal indicator scale. (cont.) Notes

Unit IV Investigation IV-X – pH scale: A number line from 0 to 14. The numbers are associated with indicator colors. – The numbers associated with indicator colors are also called pH numbers or simply pH. (cont.)

Unit IV Investigation IV-X Check-In – An unknown substance is purple with cabbage juice and does not react with calcium carbonate. Is it an acid, base or neutral substance? Explain.

Unit IV Investigation IV-X Wrap-Up – Acids and bases are different types of solutions and are classified according to their observable behavior. – Acids and bases respond differently to indicators. Depending on the indicator, different colors will form that show either an acidic or basic substance.

Toxins Unit – Investigation IV Lesson 2: Watered Down

Unit IV Investigation IV-X ChemCatalyst – Describe what you observe in the three vials. – What is one explanation for the differences you observe? – If you tested each solution with universal indicator before putting in the gummy bears, what colors would you expect to see?

Unit IV Investigation IV-X The Big Question – How does dilution affect the acidity or basicity of a solution?

Unit IV Investigation IV-X You will be able to: Explain how dilution affects the concentration and pH of a solution.

Unit IV Investigation IV-X Activity Purpose: In this activity you will examine the effect of concentration on acidity and basicity of solutions. (cont.)

Unit IV Investigation IV-X Safety note – Do not get acids and bases on your skin. In case of a spill, rinse with large amounts of water. Wear goggles. (cont.)

Unit IV Investigation IV-X Well #ConcentrationColorpH number 1.0 M HCl 0.10 M HCl M HCl M HCl M HCl M HCl M HCl M HCl M HCl Data Table for dilution of 1.0 M HCl

Unit IV Investigation IV-X Data Table for dilution of 1.0 M NaOH Well #ConcentrationColorpH number 1.0 M NaOH 0.10 M NaOH M NaOH M NaOH M NaOH M NaOH M NaOH M NaOH M NaOH

Unit IV Investigation IV-X Data Table for dilution of 1.0 M NaCl Well #ConcentrationColorpH number 1.0 M NaCl 0.10 M NaCl M NaCl M NaCl M NaCl M NaCl M NaCl M NaCl M NaCl

Unit IV Investigation IV-X Making Sense – What does concentration have to do with the acidity or basicity of a solution?

Unit IV Investigation IV-X 1470 More H + More OH – pH scale Notes (cont.)

Unit IV Investigation IV-X Arrhenius definition: – An acid is any substance that adds a hydrogen ion (H + ) to the solution. – A base is any substance that adds a hydroxide ion (OH – ) to the solution. (cont.)

Unit IV Investigation IV-X HA  H + + A – XOH  X + + OH – (cont.)

Unit IV Investigation IV-X Check-In – Lemon juice has a pH of about 2. What does this tell you about what is in the solution? – What would happen if you diluted this solution?

Unit IV Investigation IV-X Wrap-Up – The acidity and basicity of a solution are related to the concentration of the solution. Dilute solutions are less acidic and basic than more concentrated solutions. – Dilution of an acid or a base results in a solution that is increasingly neutral. (cont.)

Unit IV Investigation IV-X – The pH scale is related to the concentration of H + and OH – ions in solution. – According to Arrhenius, an acid is any substance that adds a hydrogen ion (H + ) to the solution and a base is any substance that adds a hydroxide ion (OH – ) to the solution.

Toxins Unit – Investigation IV Lesson 3: pHooey!

Unit IV Investigation IV-X ChemCatalyst Examine the following data: SubstancepH 0.10 M HCl M HCl M HCl M NaOH M NaOH M NaOH12.0 Water7.0 (cont.)

Unit IV Investigation IV-X – What do you think pH really represents? – How does the concentration of the solutions relate mathematically to the pH of the solutions? (cont.)

Unit IV Investigation IV-X The Big Question – How does pH relate to the concentrations of acidic and basic solutions?

Unit IV Investigation IV-X You will be able to: Find the pH of a solution if you know the concentrations of hydrogen or hydroxide ions that it contains.

Unit IV Investigation IV-X Activity Purpose: You will explore the relationship between pH, pOH, [H + ], and [OH – ]. (cont.)

Unit IV Investigation IV-X SubstanceAcidic or Basic? pH[H + ] (in decimal) [H + ] (in scientific notation) 1 M HCl Stomach acid (0.1 M HCl)Acidic0.1 M 1.0  10 –1 M Clear Soda M Rain WaterAcidic 1.0  10 –6 M Distilled Water M AlcoholNeutral Salt Water M Washing SodaBasic8 1.0  10 –8 M Ammonia M 1.0  10 –10 M Drain Cleaner (0.1 M NaOH) 13 1 M NaOH 1.0  M

Unit IV Investigation IV-X WellpH[H + ][OH – ]pOH A1 1.0  10 –1 M 13 B2 1.0  10 –2 M1.0  10 –12 M 12 C3 1.0  10 –3 M D4 1.0  M1.0  10 –10 M 10 E5 1.0  10 –5 M F6 1.0  10 –6 M G7 1.0  10 –7 M H7 7 I7 7 HCl

Unit IV Investigation IV-X WellpH[H + ][OH – ]pOH R7 1.0  10 –7 M 7 Q7 7 P7 O8 1.0  10 –8 M N9 1.0  10 –9 M1.0  10 –5 M 5 M101.0 x10 –10 M L  10 –11 M 3 K  10 –12 M1.0  10 –2 M J  10 –13 M1.0  10 –1 M 1 NaOH

Unit IV Investigation IV-X Making Sense – How are pH and pOH related to each other mathematically?

Unit IV Investigation IV-X This box would show 1,000 H + ions and 1,000 Cl – ions. This box would show 100 H + ions and 100 Cl – ions. Key: H + Cl – pH = 4 Notes pH = 5pH = 6pH = 7 (cont.)

Unit IV Investigation IV-X pH = –log[H + ] pOH = –log[OH – ] (cont.)

Unit IV Investigation IV-X Sample Problem: – What is the pH of a solution with a hydrogen ion concentration of 3.4  10 –4 moles/ L? (cont.)

Unit IV Investigation IV-X Please be careful when entering scientific notation into your calculator—it is very easy to make a mistake. When entering 3.4  10 –4, first enter “3.4”. Then press the button labeled “EXP” or “10 X ” or “EE”. Now enter –4, using the “+/–“ key, not the subtraction key. Never try to enter this number by pressing “X” and “10” and “–4”. (cont.)

Unit IV Investigation IV-X Check-In – What is the pH of a solution with [OH – ] = 1.0  10 –12 M?

Unit IV Investigation IV-X Wrap-Up – The relationship between pH and pOH of a solution is expressed by the following: pH + pOH = 14. – The relationship between [H + ] and [OH – ] in a solution is expressed by the following: – log [H + ] + –log [OH – ] = 14. – The pH of a solution is logarithmically related to the concentration of hydrogen ion and can be calculated mathematically using the following equation: pH =  log [H + ]